Fast retraining for transceivers in communication systems
View Patent ↗Fast retraining of communication parameters for a transceiver in a communication network. In one aspect, it is determined that the transceiver has lost the communication link for data communication, and the transceiver receives a signal providing a fast retraining sequence that updates transceiver parameters in order to reacquire the link for the data communication. The fast retraining sequence is performed in a reduced time relative to a full training sequence used for initializing the parameters for data communication by the transceiver.
1. A method of signaling along a link between respective Ethernet transceivers, the method comprising:
performing a pre-defined full training sequence to train a set of link parameters associated with the Ethernet transceivers, the full training sequence including a plurality of steps including transmission of a first DSQ128 training signal;
transmitting operational data along the link based on the trained link parameters;
detecting a link condition preventing operational data transmission above a threshold criteria;
re-training the link in response to the detecting, the re-training having a sequence of steps fewer in number than the full training plurality of steps, the re-training comprising:
exchanging a first PAM-2 training signal between the transceivers;
exchanging a second PAM-2 training signal encoded in accordance with a Tomlinson-Harashima Precoding (THP) type of encoding; and
exchanging a second DSQ128 training signal.
2. The method according to claim 1 wherein:
the full training sequence plurality of steps comprises at least four from the group comprising auto-negotiating, backing-off power, calibrating front end components, changing frequency offsets, exchanging a third PAM-2 training signal, exchanging a fourth PAM-2 training signal encoded in accordance with a THP type of precoding, and exchanging a third PAM-16 training signal.
3. The method according to claim 1 wherein:
while transmitting operational data, adapting one or more of the trained parameters based on received operational data.
4. The method according to claim 1 wherein the re-training sequence comprises asymmetrically re-training.
5. The method module according to claim 4 wherein asymmetrically re-training comprises:
receiving a re-training sequence from a first transmitter in a first of the respective transceivers; and
receiving operational data from a second transmitter in a second of the respective transmitters.
6. The method according to claim 1 wherein the re-training sequence comprises symmetrically re-training.
7. The method according to claim 6 wherein symmetrically re-training comprises:
receiving a first re-training sequence from a first transmitter in a first of the respective transceivers; and
receiving a second re-training sequence from a second transmitter in a second of the respective transceivers.
8. The method according to claim 7 wherein exchanging a second PAM-2 training signal encoded in accordance with a Tomlinson-Harashima Precoding (THP) type of encoding comprises:
encoding a PAM-2 training signal in accordance with a THP algorithm having coefficients determined in a manner that compensates for known attenuation in the link.
9. The method according to claim 8 wherein the known attenuation comprises attenuation due to filtering from a notch filter.
10. The method according to claim 1 wherein the re-training sequence is carried out in a sequential manner in accordance with an Infofield exchange protocol.
11. The method according to claim 1 wherein the link condition is determined based on a detected signal-to-noise ratio.
12. The method according to claim 1 wherein the link condition is determined based on a detected bit error rate.
13. The method according to claim 12 wherein the detected bit error rate is determined based on decoding data encoded in accordance with a low-density-parity-check (LDPC) algorithm.
14. The method according to claim 12 wherein the link condition is determined based on a predetermined number of consecutive frames having bit errors.
15. The method according to claim 12 wherein the link condition is determined based on a bit error rate above a predetermined threshold.
16. An Ethernet transceiver for transmitting and receiving PAM-16 signals, the transceiver comprising:
a first receiver having circuitry for setting receiver operating parameters in response to a first full training sequence transmitted from a first transmitter, the full training sequence comprising a plurality of steps;
a second transmitter having transmitter operating parameters set in accordance with a second full training sequence, the second full training sequence for transmission to a second receiver;
detection circuitry to identify a signaling condition during transmission of operational data between the first receiver and the first transmitter wherein the first receiver fails to receive data with respect to a signal quality threshold; and
wherein in response to the identified signaling condition, the first transmitter operative to send a re-train request to the second receiver, such that the second transmitter transmits a re-training sequence to the first receiver, the re-training sequence comprising steps fewer in number than the full training sequence plurality of steps and at least a transmission of precoding coefficients from the first transmitter to the first receiver.
17. The Ethernet transceiver according to claim 16 wherein the first receiver and the second transmitter are disposed on the same integrated circuit chip.
18. The Ethernet transceiver according to claim 16 wherein the signal quality threshold comprises a detected signal-to-noise ratio.
19. The Ethernet transceiver according to claim 16 wherein the signal quality threshold comprises a detected bit error rate.
20. The Ethernet transceiver according to claim 16 wherein the first receiver receives the re-training sequence while the second transmitter transmits operational data.
21. The Ethernet transceiver according to claim 16 wherein the first receiver receives the re-training sequence while the first transmitter transmits a second re-training sequence.
22. The Ethernet transceiver according to claim 21 wherein the first and second re-training sequences comprise an exchange of pre-coding coefficients from the first and second transmitters to the respective first and second receivers.
23. A method of signaling along a link between respective Ethernet transceivers, the method comprising:
performing a pre-defined full training sequence to train a set of link parameters associated with the ethernet transceivers, the full training sequence including a plurality of steps to establish initial operating characteristics, and including transmission of a first DSQ128 training signal;
transmitting operational data along the link based on the trained link parameters;
detecting a link condition preventing operational data transmission above a threshold criteria; and
re-training the link in response to the detecting, the re-training based on the initial operating characteristics and having a sequence of steps fewer in number than the full training plurality of steps.